Albinism Workup

Updated: Mar 22, 2016
  • Author: Mounir Bashour, MD, PhD, CM, FRCSC, FACS; Chief Editor: Hampton Roy, Sr, MD  more...
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Workup

Laboratory Studies

Hair bulb assays help to indicate the status of tyrosinase activity. Hair bulbs are taken from the scalp, and the catalytic activity of tyrosinase is determined either by incubation in DOPA and consequential induction of melanin determined by visual inspection or by a radioactive biochemical assay in which the samples are incubated with a radiolabeled tyrosine precursor and the amount of radiolabel released after enzymatic conversion quantified spectrophotometrically. The usefulness of this test is debatable because a negative result indicates oculocutaneous albinism (OCA) 1A, but a positive result still leaves the possibility of OCA 1, OCA 2, OCA 3, or OA 1.

The most definitive test in determining the albinism type is genetic sequence analysis. Of course, the test is useful only for families with individuals who have albinism. The test cannot be used as a screening tool.

Genetic sequence analysis can be used to determine if a fetus has albinism. Amniocentesis at 16-18 weeks could be performed to obtain a sample for analysis. However, parents should be aware that children with albinism could function well and have a good prognosis.

Obtain a bleeding time if the patient is planning to undergo surgery. Some physicians believe that a bleeding time should be obtained in all albino persons. If Hermansky-Pudlak syndrome (HPS) is suspected, bleeding time, platelet aggregation, and platelet electron microscopy is necessary.

If Chediak-Higashi syndrome (CHS) is suspected, a hematologist should evaluate polymorphonuclear leukocyte function.

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Imaging Studies

Macular optical coherence tomography  [7, 8]

Handheld ultra-high-resolution spectral-domain optical coherence tomography (SD-OCT) can be used in young children with nystagmus and other ocular problems to classify foveal abnormalities and help determine the cause of the infantile nystagmus with the use of foveal morphology.

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Other Tests

Visual-evoked potential tests

Sweep visual-evoked potential (VEP) testing can be used as a predictive tool for recognition acuity in children with albinism. Predictability was found in a clinical spectrum of albinism. [9]

Pattern-appearance VEP shows a strong association between the magnitude of the interhemispheric latency asymmetry and the clinical signs of albinism. [10]

Flash VEP also shows a strong association between the magnitude of the interhemispheric latency asymmetry and the clinical signs of albinism. [10]

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Histologic Findings

Histologic examination of the skin of male patients with this condition and female carriers of OA1 reveals the presence of macromelanosomes.

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